The mqtt_publish node

Publish data to a mqtt-broker. Incoming data is converted to JSON before sending.

If the save() parameter is given, every message first gets stored to an on-disk queue before sending, this way we can make sure no message gets lost when disconnected from the broker.

Note: This node is a sink node and does not output any flow-data, therefore any node connected to this node will not get any data.

Example

def topic = 'top/track/pressure'

|mqtt_publish() 
.topic(topic)
.retained()

Using a lambda expression for the topic:

def topic_base = 'top/'

|mqtt_publish()
.topic_lambda(lambda: str_concat([topic_base, "type", '/', "measurement"])

Here the topic string is built with a lambda expression using the topic_base declaration, the string '/' and two fields from the current data_point. The topic string may be a different one with every data_point that gets published.

Parameters

Parameter	Description	Default
host( string )	Ip address or hostname of the broker	config: mqtt.host/FAXE_MQTT_HOST
port( integer )	The broker's port	config: mqtt.port/FAXE_MQTT_PORT
user( string )	username	config: mqtt.user/FAXE_MQTT_USER
pass( string )	password	config: mqtt.pass/FAXE_MQTT_PASS
client_id( string )	mqtt client id, defaults to a combination of flow-id and node-id	undefined
topic( string )	mqtt topic to use	undefined
topic_lambda( lambda )	mqtt topic to use evaluated via a lambda expression	undefined
topic_field( string )	[since 0.19.9] path to a field in the current data-item, who's value should be used as the topic	undefined
qos( integer )	Quality of service, one of 0, 1 or 2	1
retained( is_set )	whether the message should be retained on the broker	false (not set)
save( is_set )	send save (on-disk queuing)	false (not set)
ssl( is_set )	whether to use ssl	config: mqtt.ssl.enable/FAXE_MQTT_SSL_ENABLE

topic or topic_lambda or topic_field must be provided.